Hi Beersy,
I haven't personally been to Shiga Kogen but I found the snow japan site really helpful when I was planning my trips to Japan.
Take a look here -
http://www.snowjapan.com/e/spotlight/shiga-kogen.html&
www.snowjapan.com/e/hotel/nagano-shiga-kogen-accommodation.php Also the snow japan forums are really friendly and helpful with this kind of stuff.
I've been snowboarding in Japan twice in Feb 08 & 09 but both to Hakuba, if you decide that you are going to head to Hak instead, let me know and I can help you with some more information.
Also, I'd suggest getting a flexible 4 day JR east rail pass. If you are staying in Tokyo the night you arrive it makes travel heaps easier. We used it from the airport to Tokyo, then out to Hakuba and from Hakuba back to the Tokyo. The last day we used from Hakuaba to Matsumoto for a day trip to the castle.
www.jreast.co.jp/e/eastpass/Japan is heaps of fun, more powder than you've every seen.
Have an awesome time.
Yes I know, strange first post. However I've been reading these forums for a little while now (decided that as I'm not going OS this summer to snowboard, I might take up kiteboarding like I've saying to myself for years) and after reading this thread decided to join.